missed an inward invoice in gstr-3b

I placed an order for purchase of some articles from xyz company, the sale invoice for which was generated by xyz on 28th Aug and articles were dispatched on 01st September. Due to Transit delay or whatever reason, I received the purchase invoice and articles on 22nd September and hence I was not able to reflect neither this particular purchase nor corresponding itc in gstr-3b of August. Now should I reflect such purchases in gstr-3b of September or should wait for gstr 3 of August to be filled.